World powers and Iran have formally announced a comprehensive nuclear accord.

Federica Mogherini, the European Union's foreign policy chief, says, "Today is an historic day." She said it was a great honor "for us to announce that we have reached an agreement on the Iranian nuclear issue."

Iranian President Hassan Rouhani dismissed claims that the Islamic Republic sought to make atomic weapons under its nuclear program. Speaking live in a nationwide televised address, Rouhani said: "Iran has never sought to manufacture a nuclear weapon and will never seek to manufacture a nuclear weapon.

President Barack Obama says the landmark nuclear deal with Iran "is not built on trust, it is built on verification."

Obama says all of Iran's pathways to a nuclear weapon are cut off under the terms of the agreement announced Tuesday. The president says Iran will remove two-thirds of its installed centrifuges and get rid of 98 percent of its stockpile of uranium.

In exchange, the president says Iran will receive phased in sanctions relief as it fulfills the provisions in the deal.

Obama threatened to veto any congressional legislation that would seek to block implementation of the agreement. He says that no deal "means a greater change of more war" in the Middle East.